Several methods for attaching a cushion material (a foamed body) structure to a body portion of a car seat with a skin material attached on its surface have been known and used in public, specifically as a method of attaching a skin material to the cushion material in a concave surface shape to secure the concave surface shape of a seating part of the seat. In the prior art, a method of adhering a whole back surface of the skin over a surface of the cushion material and a method such as an integral molding method of injecting urethane into a cushion material molding die by setting a skin material therein have been often used. However, in either method, their own production systems for carrying out such methods are required, and it is difficult to install such systems in a continuous assembly line, thereby increasing the cost for transferring and manipulating materials. Also, such a method in the prior art is a mass production system and it is thus required to maintain its operation rate. However, it is difficult to control a volume corresponding to a variation of the production rate. Thus, such a production method results in low productivity and causes a rise in cost. In order to avoid such disadvantages, a planar fastening material is used for attaching a surface material on cushioning material. This planar fastening material is called a planar fastener or planar fastening material. The planar fastening material is a knitted or textile base sheet containing a large number of hooked or ting-shaped small protrusions thereon. The hooked or ring-shaped small protrusions can be fixed to the skin by fastening to the back surface of the skin material and is found to be superior for its separating or shearing and attaching properties. However, if this planar fastening material is used for an integral molding in a cushion material molding die, in contrast with an advantage of means for fastening a skin material which is low cost, a disadvantage results which is an impregnation and hardening of the solution of the cushion material to a supporting material of the planar fastening material is caused. Specifically, while it is desirable to attach the side end of the planar material with a space which is slightly apart from the side portion of the cushion material, a hard impregnation layer is formed by impregnation of the solution of the cushion material into the planar fastening body, in particular, the periphery of the supporting material adjacent the space. This impregnation layer makes a feeling of physical discomfort for a person who sits thereon because it can be felt through a skin covering the cushion material and also it can be felt by touching and moving his or her body thereon.
Therefore, an object of the present invention is, in a cushion body structure of a car seat which is made by fastening a skin material to a cushion material through a planar fastening body connected by a supporting material having a constant thickness to a back surface of a planar fastening material, to provide a cushion body structure of a car seat comfortable to sit upon which is made by forming a nonimpregnation layer which does not absorb a foamed solution of the cushion material in the periphery of the planar fastening material and the supporting material positioned on its back surface.